package com.sunday.common.widgets.gridview;

import java.util.LinkedList;
import java.util.List;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.os.Handler;
import android.os.Vibrator;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnPreDrawListener;
import android.view.WindowManager;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ListAdapter;

import com.sunday.common.widgets.gridview.DragGridBaseAdapter;


/**
 * 可拖拽的GridView, 添加Item的交换效果
 *
 * @blog http://blog.csdn.net/xiaanming 
 *
 * @author xiaanming
 *
 */
public class DragGridView extends GridView{
	/**
	 * DragGridView的item长按响应的时间， 默认是1000毫秒，也可以自行设置
	 */
	private long dragResponseMS = 1000;

	/**
	 * 是否可以拖拽，默认不可以
	 */
	private boolean isDrag = false;

	private int mDownX;
	private int mDownY;
	private int moveX;
	private int moveY;
	/**
	 * 正在拖拽的position
	 */
	private int mDragPosition;

	/**
	 * 刚开始拖拽的item对应的View
	 */
	private View mStartDragItemView = null;

	/**
	 * 用于拖拽的镜像，这里直接用一个ImageView
	 */
	private ImageView mDragImageView;

	/**
	 * 震动器
	 */
	private Vibrator mVibrator;

	private WindowManager mWindowManager;
	/**
	 * item镜像的布局参数
	 */
	private WindowManager.LayoutParams mWindowLayoutParams;

	/**
	 * 我们拖拽的item对应的Bitmap
	 */
	private Bitmap mDragBitmap;

	/**
	 * 按下的点到所在item的上边缘的距离
	 */
	private int mPoint2ItemTop ;

	/**
	 * 按下的点到所在item的左边缘的距离
	 */
	private int mPoint2ItemLeft;

	/**
	 * DragGridView距离屏幕顶部的偏移量
	 */
	private int mOffset2Top;

	/**
	 * DragGridView距离屏幕左边的偏移量
	 */
	private int mOffset2Left;

	/**
	 * 状态栏的高度
	 */
	private int mStatusHeight;

	/**
	 * DragGridView自动向下滚动的边界值
	 */
	private int mDownScrollBorder;

	/**
	 * DragGridView自动向上滚动的边界值
	 */
	private int mUpScrollBorder;

	/**
	 * DragGridView自动滚动的速度
	 */
	private static final int speed = 20;
	/**
	 * item的移动动画是否结束
	 */
	private boolean mAnimationEnd = true;

	private DragGridBaseAdapter mDragAdapter;
	/**
	 * GridView的列数
	 */
	private int mNumColumns;
	/**
	 * 当GridView的numColumns设置为AUTO_FIT，我们需要计算GirdView具体的列数
	 */
	private int mColumnWidth;
	/**
	 * GridView是否设置了numColumns为具体的数字
	 */
	private boolean mNumColumnsSet;
	private int mHorizontalSpacing;
	private int mVerticalSpacing;

	public DragGridView(Context context) {
		this(context, null);
	}

	public DragGridView(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public DragGridView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
		mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
		mStatusHeight = getStatusHeight(context); //获取状态栏的高度

		if(!mNumColumnsSet){
			mNumColumns = AUTO_FIT;
		}

	}

	/**
	 * 删除item的动画效果
	 * @param position
	 */
	public void removeItemAnimation(final int position){
		mDragAdapter.removeItem(position);
		final ViewTreeObserver observer = getViewTreeObserver();
		observer.addOnPreDrawListener(new OnPreDrawListener() {

			@Override
			public boolean onPreDraw() {
				observer.removeOnPreDrawListener(this);
				animateReorder(position, getLastVisiblePosition() + 1 );
				return true;
			}
		} );
	}

	private Handler mHandler = new Handler();

	//用来处理是否为长按的Runnable
	private Runnable mLongClickRunnable = new Runnable() {

		@Override
		public void run() {
			isDrag = true; //设置可以拖拽
			mVibrator.vibrate(50); //震动一下
			mStartDragItemView.setVisibility(View.INVISIBLE);//隐藏该item

			//根据我们按下的点显示item镜像
			createDragImage(mDragBitmap, mDownX, mDownY);
		}
	};


	@Override
	public void setAdapter(ListAdapter adapter) {
		super.setAdapter(adapter);

		if(adapter instanceof DragGridBaseAdapter){
			mDragAdapter = (DragGridBaseAdapter) adapter;
		}else{
			throw new IllegalStateException("the adapter must be implements DragGridAdapter");
		}
	}

	/**
	 * 获取列数
	 */
	@Override
	public void setNumColumns(int numColumns) {
		super.setNumColumns(numColumns);
		mNumColumnsSet = true;
		this.mNumColumns = numColumns;
	}

	/**
	 * 获取设置的列宽
	 */
	@Override
	public void setColumnWidth(int columnWidth) {
		super.setColumnWidth(columnWidth);
		mColumnWidth = columnWidth;
	}

	/**
	 * 获取水平方向的间隙
	 */
	@Override
	public void setHorizontalSpacing(int horizontalSpacing) {
		super.setHorizontalSpacing(horizontalSpacing);
		this.mHorizontalSpacing = horizontalSpacing;
	}


	/**
	 * 获取竖直方向的间隙
	 */
	@Override
	public void setVerticalSpacing(int verticalSpacing) {
		super.setVerticalSpacing(verticalSpacing);
		this.mVerticalSpacing = verticalSpacing;
	}

	/**
	 * 若列数设置为AUTO_FIT，我们在这里面计算具体的列数
	 */
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		if (mNumColumns == AUTO_FIT) {
			int numFittedColumns;
			if (mColumnWidth > 0) {
				int gridWidth = Math.max(MeasureSpec.getSize(widthMeasureSpec) - getPaddingLeft()
						- getPaddingRight(), 0);
				numFittedColumns = gridWidth / mColumnWidth;
				if (numFittedColumns > 0) {
					while (numFittedColumns != 1) {
						if (numFittedColumns * mColumnWidth + (numFittedColumns - 1)
								* mHorizontalSpacing > gridWidth) {
							numFittedColumns--;
						} else {
							break;
						}
					}
				} else {
					numFittedColumns = 1;
				}
			} else {
				numFittedColumns = 2;
			}
			mNumColumns = numFittedColumns;
		}

		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
	}

	/**
	 * 设置响应拖拽的毫秒数，默认是1000毫秒
	 * @param dragResponseMS
	 */
	public void setDragResponseMS(long dragResponseMS) {
		this.dragResponseMS = dragResponseMS;
	}

	@Override
	public boolean dispatchTouchEvent(MotionEvent ev) {
		switch(ev.getAction()){
			case MotionEvent.ACTION_DOWN:
				mDownX = (int) ev.getX();
				mDownY = (int) ev.getY();

				//根据按下的X,Y坐标获取所点击item的position
				mDragPosition = pointToPosition(mDownX, mDownY);


				if(mDragPosition == AdapterView.INVALID_POSITION){
					return super.dispatchTouchEvent(ev);
				}

				//使用Handler延迟dragResponseMS执行mLongClickRunnable
				mHandler.postDelayed(mLongClickRunnable, dragResponseMS);

				//根据position获取该item所对应的View
				mStartDragItemView = getChildAt(mDragPosition - getFirstVisiblePosition());

				//下面这几个距离大家可以参考我的博客上面的图来理解下
				mPoint2ItemTop = mDownY - mStartDragItemView.getTop();
				mPoint2ItemLeft = mDownX - mStartDragItemView.getLeft();

				mOffset2Top = (int) (ev.getRawY() - mDownY);
				mOffset2Left = (int) (ev.getRawX() - mDownX);

				//获取DragGridView自动向上滚动的偏移量，小于这个值，DragGridView向下滚动
				mDownScrollBorder = getHeight() / 5;
				//获取DragGridView自动向下滚动的偏移量，大于这个值，DragGridView向上滚动
				mUpScrollBorder = getHeight() * 4/5;


				//开启mDragItemView绘图缓存
				mStartDragItemView.setDrawingCacheEnabled(true);
				//获取mDragItemView在缓存中的Bitmap对象
				mDragBitmap = Bitmap.createBitmap(mStartDragItemView.getDrawingCache());
				//这一步很关键，释放绘图缓存，避免出现重复的镜像
				mStartDragItemView.destroyDrawingCache();

				break;
			case MotionEvent.ACTION_MOVE:
				int moveX = (int)ev.getX();
				int moveY = (int) ev.getY();

				//如果我们在按下的item上面移动，只要不超过item的边界我们就不移除mRunnable
				if(!isTouchInItem(mStartDragItemView, moveX, moveY)){
					mHandler.removeCallbacks(mLongClickRunnable);
				}
				break;
			case MotionEvent.ACTION_UP:
				mHandler.removeCallbacks(mLongClickRunnable);
				mHandler.removeCallbacks(mScrollRunnable);
				break;
		}
		return super.dispatchTouchEvent(ev);
	}


	/**
	 * 是否点击在GridView的item上面
	 * @param dragView
	 * @param x
	 * @param y
	 * @return
	 */
	private boolean isTouchInItem(View dragView, int x, int y){
		if(dragView == null){
			return false;
		}
		int leftOffset = dragView.getLeft();
		int topOffset = dragView.getTop();
		if(x < leftOffset || x > leftOffset + dragView.getWidth()){
			return false;
		}

		if(y < topOffset || y > topOffset + dragView.getHeight()){
			return false;
		}

		return true;
	}



	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		if(isDrag && mDragImageView != null){
			switch(ev.getAction()){
				case MotionEvent.ACTION_MOVE:
					moveX = (int) ev.getX();
					moveY = (int) ev.getY();

					//拖动item
					onDragItem(moveX, moveY);
					break;
				case MotionEvent.ACTION_UP:
					onStopDrag();
					isDrag = false;
					break;
			}
			return true;
		}
		return super.onTouchEvent(ev);
	}


	/**
	 * 创建拖动的镜像
	 * @param bitmap
	 * @param downX
	 * 			按下的点相对父控件的X坐标
	 * @param downY
	 * 			按下的点相对父控件的X坐标
	 */
	private void createDragImage(Bitmap bitmap, int downX , int downY){
		mWindowLayoutParams = new WindowManager.LayoutParams();
		mWindowLayoutParams.format = PixelFormat.TRANSLUCENT; //图片之外的其他地方透明
		mWindowLayoutParams.gravity = Gravity.TOP | Gravity.LEFT;
		mWindowLayoutParams.x = downX - mPoint2ItemLeft + mOffset2Left;
		mWindowLayoutParams.y = downY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
		mWindowLayoutParams.alpha = 0.55f; //透明度
		mWindowLayoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
		mWindowLayoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
		mWindowLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
				| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE ;

		mDragImageView = new ImageView(getContext());
		mDragImageView.setImageBitmap(bitmap);
		mWindowManager.addView(mDragImageView, mWindowLayoutParams);
	}

	/**
	 * 从界面上面移动拖动镜像
	 */
	private void removeDragImage(){
		if(mDragImageView != null){
			mWindowManager.removeView(mDragImageView);
			mDragImageView = null;
		}
	}

	/**
	 * 拖动item，在里面实现了item镜像的位置更新，item的相互交换以及GridView的自行滚动
	 * @param moveX
	 * @param moveY
	 */
	private void onDragItem(int moveX, int moveY){
		mWindowLayoutParams.x = moveX - mPoint2ItemLeft + mOffset2Left;
		mWindowLayoutParams.y = moveY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
		mWindowManager.updateViewLayout(mDragImageView, mWindowLayoutParams); //更新镜像的位置
		onSwapItem(moveX, moveY);

		//GridView自动滚动
		mHandler.post(mScrollRunnable);
	}


	/**
	 * 当moveY的值大于向上滚动的边界值，触发GridView自动向上滚动
	 * 当moveY的值小于向下滚动的边界值，触发GridView自动向下滚动
	 * 否则不进行滚动
	 */
	private Runnable mScrollRunnable = new Runnable() {

		@Override
		public void run() {
			int scrollY;
			if(getFirstVisiblePosition() == 0 || getLastVisiblePosition() == getCount() - 1){
				mHandler.removeCallbacks(mScrollRunnable);
			}

			if(moveY > mUpScrollBorder){
				scrollY = speed;
				mHandler.postDelayed(mScrollRunnable, 25);
			}else if(moveY < mDownScrollBorder){
				scrollY = -speed;
				mHandler.postDelayed(mScrollRunnable, 25);
			}else{
				scrollY = 0;
				mHandler.removeCallbacks(mScrollRunnable);
			}

			smoothScrollBy(scrollY, 10);
		}
	};


	/**
	 * 交换item,并且控制item之间的显示与隐藏效果
	 * @param moveX
	 * @param moveY
	 */
	private void onSwapItem(int moveX, int moveY){
		//获取我们手指移动到的那个item的position
		final int tempPosition = pointToPosition(moveX, moveY);

		//假如tempPosition 改变了并且tempPosition不等于-1,则进行交换
		if(tempPosition != mDragPosition && tempPosition != AdapterView.INVALID_POSITION && mAnimationEnd){
			/**
			 * 交换item
			 */
			mDragAdapter.reorderItems(mDragPosition, tempPosition);
			/**
			 * 设置新到的位置隐藏
			 */
			mDragAdapter.setHideItem(tempPosition);

			final ViewTreeObserver observer = getViewTreeObserver();
			observer.addOnPreDrawListener(new OnPreDrawListener() {

				@Override
				public boolean onPreDraw() {
					observer.removeOnPreDrawListener(this);
					animateReorder(mDragPosition, tempPosition);
					mDragPosition = tempPosition;
					return true;
				}
			} );

		}
	}

	/**
	 * 创建移动动画
	 * @param view
	 * @param startX
	 * @param endX
	 * @param startY
	 * @param endY
	 * @return
	 */
	private AnimatorSet createTranslationAnimations(View view, float startX,
													float endX, float startY, float endY) {
		ObjectAnimator animX = ObjectAnimator.ofFloat(view, "translationX",
				startX, endX);
		ObjectAnimator animY = ObjectAnimator.ofFloat(view, "translationY",
				startY, endY);
		AnimatorSet animSetXY = new AnimatorSet();
		animSetXY.playTogether(animX, animY);
		return animSetXY;
	}


	/**
	 * item的交换动画效果
	 * @param oldPosition
	 * @param newPosition
	 */
	private void animateReorder(final int oldPosition, final int newPosition) {
		boolean isForward = newPosition > oldPosition;
		List<Animator> resultList = new LinkedList<Animator>();
		if (isForward) {
			for (int pos = oldPosition; pos < newPosition; pos++) {
				View view = getChildAt(pos - getFirstVisiblePosition());
				if ((pos + 1) % mNumColumns == 0) {
					resultList.add(createTranslationAnimations(view,
							- (view.getWidth() + mHorizontalSpacing) * (mNumColumns - 1), 0,
							view.getHeight() + mVerticalSpacing, 0));
				} else {
					resultList.add(createTranslationAnimations(view,
							view.getWidth() + mHorizontalSpacing, 0, 0, 0));
				}
			}
		} else {
			for (int pos = oldPosition; pos > newPosition; pos--) {
				View view = getChildAt(pos - getFirstVisiblePosition());
				if ((pos) % mNumColumns == 0) {
					resultList.add(createTranslationAnimations(view,
							(view.getWidth() + mHorizontalSpacing) * (mNumColumns - 1), 0,
							-view.getHeight() - mVerticalSpacing, 0));
				} else {
					resultList.add(createTranslationAnimations(view,
							-view.getWidth() - mHorizontalSpacing, 0, 0, 0));
				}
			}
		}

		AnimatorSet resultSet = new AnimatorSet();
		resultSet.playTogether(resultList);
		resultSet.setDuration(300);
		resultSet.setInterpolator(new AccelerateDecelerateInterpolator());
		resultSet.addListener(new AnimatorListenerAdapter() {
			@Override
			public void onAnimationStart(Animator animation) {
				mAnimationEnd = false;
			}

			@Override
			public void onAnimationEnd(Animator animation) {
				mAnimationEnd = true;
			}
		});
		resultSet.start();
	}

	/**
	 * 停止拖拽我们将之前隐藏的item显示出来，并将镜像移除
	 */
	private void onStopDrag(){
		View view = getChildAt(mDragPosition - getFirstVisiblePosition());
		if(view != null){
			view.setVisibility(View.VISIBLE);
		}
		mDragAdapter.setHideItem(-1);
		removeDragImage();
	}

	/**
	 * 获取状态栏的高度
	 * @param context
	 * @return
	 */
	private static int getStatusHeight(Context context){
		int statusHeight = 0;
		Rect localRect = new Rect();
		((Activity) context).getWindow().getDecorView().getWindowVisibleDisplayFrame(localRect);
		statusHeight = localRect.top;
		if (0 == statusHeight){
			Class<?> localClass;
			try {
				localClass = Class.forName("com.android.internal.R$dimen");
				Object localObject = localClass.newInstance();
				int i5 = Integer.parseInt(localClass.getField("status_bar_height").get(localObject).toString());
				statusHeight = context.getResources().getDimensionPixelSize(i5);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return statusHeight;
	}

}
